An Analytical Perspective on Determination of Free Base Nicotine in E-Liquids

Table 2

Determination of free base nicotine in standard solutions by hexane-water double extraction.

	pH	% free base nicotine by Henderson–Hasselbalch equation	% experimental free base nicotine	% difference	Mean % difference	Std. dev.
Nicotine std (0.8 mg/mL)	5.01	0.07	0.33	NA	NA	NA
			0.26	NA
			0.25	NA
	7.06	7.22	8.81	22.01	21.37	0.71
			8.77	21.50
			8.71	20.59
	9.00	87.14	63.33	27.32	26.92	0.35
			63.88	26.70
			63.83	26.75
	11.00	99.85	75.20	24.69	24.12	0.59
			76.37	23.52
			75.74	24.15
	13.00	100.00	81.08	18.92	18.23	0.63
			81.90	18.10
			82.32	17.68
				Avg.	22.66 ± 3.72

Note. Extraction efficiency was calculated as “100 – mean % difference.” (77.34 ± 3.72%). NA: not applicable, since the % free base nicotine values are <1.